Diagnosability Analysis for Web Services with Constraint-based Models

In this paper we deal with the problem of model-based diagnosability analysis for Web Services. The goal of diagnosability analysis is to determine whether the information one can observe during service execution is sufficient to precisely locate (by means of diagnostic reasoning) the source of the problem. The major difficulty in the context of Web Services is that models are distributed and no single entity has a global view of the complete model. In the paper we propose an approach that determines diagnosability for the decentralized diagnostic framework, based on a Supervisor coordinating several Local Diagnosers. We also show that diagnosability analysis can be performed without requiring the Local Diagnosers different operations than those needed for diagnosis. The diagnosability of each fault mode is first analyzed independently of the occurrence of other faults, then the results are used to analyze some combinations of modes explicitly, and leave the analysis of other combinations implicit, to avoid an exhaustive check.